美国食品和药物管理局 Krause等的血清流行病学研究显示 ,水痘疫苗接种后血清抗体滴度降低时 ,Oka疫苗株可再活化 ,增强宿主对水痘病毒的免疫力。对野型病毒的再接触和潜伏疫苗病毒的再活化相结合可保持对野型水痘病毒的终身免疫力。　　Krause等分析了 46 31名儿童的血清抗体 Serological epidemiological studies by Krause et al. Of the U.S. Food and Drug Administration showed that when the serum antibody titer after varicella vaccination is reduced, the Oka vaccine strain can be reactivated, enhancing the host’s immunity against the varicella virus. The re-exposure to wild-type virus combined with the reactivation of latent vaccine virus maintains the lifelong immunity to wild-type varicella virus. Krause et al. Analyzed serum antibodies in 46 31 children